Fuel fired heater



May 24, 1960 R. E. TEAGLE 2,937,8@0

FUEL FIRED HEATER Filed ivay 23, 1958 2 Sheets-Sheet l RICHARD E. T EAG LE ATTORNEYS 2 Sheets-Sheet 2 Filed vay 25, 1958 INVENTOR. RICHARD E. TEAGLE ATTORNEYS FUEL FIRED HEATER Richard E. Teagle, Parma, Ohio, assignor to The Foundry Equipment Company, Cleveland, Ohio, a corporation of Ohio Filed May z3, 195s, ser. No. 737,414` 6 claims. (crass- 19) This invention relates as indicatedto a fuel tired heater, and more particularly to a heater desired to deliver a supply of hot air and gases tolarge foundryy molds for the purpose of drying them. It is alsosuitable forwuse in many installations where an efficient automatically controlled heater is desired. Y

VFuel tired heaters and particularly gas tired heaters are frequently employed for the purpose of delivering a considerable volume of heated air and gases to thefinteriors of large foundry molds to dry the latter prior to casting. For this purpose, large so-called portablel heaters have often been utilized which, however, are so heavy and cumbersome that an overhead cranel is required -to shift them from place to place where needed. Sometimes rather elaborate duct-work has also-been required. When relatively small and light heaters. of a truly portable nature have been provided comprising principally a burner.

and a propellerfan, insuiiicient heat is extracted. from the heater for efficient operation. In practice, it is fre-i quently important that the air delivered froml theheater be at a predetermined temperature not affected byducty back pressure and the like.

It is accordingly an important object ofmy invention to provide a novel fuel fired heater adapted to deliver a considerable volume of heated air and gases at a pre` selected temperature regardless-of variation in such volurne and pressure.

Staes Patent 2 high'pressure fan 4. Burner Zftsfwithin an'innersheet metal shell Sentirely enclosed within an outer sheet metal housing..6 providingair passages 7, 8, 9 and 10 there between. Such inner shell 5 may desirably projectslight. ly. beyond outer housing 6 providing an outlet 11 adapted to be connected to a large mold to be dried or to appro# priate duct-work as desired. Cool air is thus admitted around the entire periphery of such outlet 11 and passes inwardly through ductsl 7, 8, 9 and 10 to the chamber 12 containing fan housing 13. Air is drawn into such housingthrough opening 14 generallyco-axal with -fan 4 and thendriven by such fan pastv burners 2 out of delivery orifice 11. Such airis heated by the burners and also supplies; the necessary oxygen for complete combustion of thetburner fuel. The inner shell 5 may be very highly heated bythe burner and thereby further contribute to heating ofthe air forcedthrough the shell by fan 4. The incoming air inpassages 7, 8,9 and 10is, of course, pre-A heated toV some extent. by the hot walls of the inner shell and also serve'szasv an effective insulating medium for the outer housing 6. Heavyand expensive insulating vmaterials are accordingly not required suchas are ordinarily foundinthe usual heater;

Fan 4'is desirably a high pressure fan driven by motor 15 mountedon platform 1.

' The burner 2` .may be of generally conventional cross l shape design withv ports" opening toward the delivery` ori lice 11 of inner: shell 5.. An appropriate gas-air mixture? may be delivered tov such burner throughduct 16'. Suchgas-air mixture is delivered to duct 16 by mixer-blower 3 driven by motor 17, airv being drawninto such blowery through adjustably. louvered` air inlet shutterv 18. vvGas* suchas naturalfgas may be admitted through gasinlet` valve 19 adapted to be connected by. means of coupling. 20y to a gas supply'line and' thence through a conven-v tional safety'shut-oif valve 21 to the air in1et'22. The.

Another object is toprovide such` heater which will v be readily portable and inexpensive but nevertheless highly efficient in operation.

Still another. object is to provide such .heater yutilizing al.

counterflow air system having the advantage ofi bothutilizing the heated surfaces to the maximum; and alsosub-' stantially eliminating the outer insulation required.y

A further object is to provide. an integrated'L burner fan unit of improved design.

Other objects of the invention will appear asy the de` A scription proceeds.

l To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims', the following description and the annexed drawing setting forth in detail certain illustrative embodiments` of the invention, these being indicative, however, of but a few of the' various ways in which the principle of the invention may be employed.

In said annexed drawing:

Fig. l is a top plan view, partly in section, of a heater embodying the principles of my invention;

Fig. 2 is a transverse section taken on the line 2--2 on Fig. l; and

Fig. 3` is a side elevation on an enlarged scale. Referring now more particularly to such drawing, the

embodiment of my invention there illustrated comprises a welded metal base or platform 1 on which the several components are mounted. These componentscomprise principally a burner 2, a blower 3 anda comparatively blower 3 thoroughly mixes the gas and air and delivers:

such mixtureto burner 2L The blower 3 will be driven atconstantsspeedtbp'rnotoriv 17 and the shutter 18 will be adjusted 'to-vary; the; air;

intake., Thus, it may be assumed thatfsuch shutter iszsettat a halfopen positionfor the purpose ,of the followings` explanation. When tn'eshutterY is thus movedl fi'omtfull;

open to half o'penrposition,y there willy beacdnse'qujent drop in pressure within conduit 16/leadingfrornxmixer: f blower 3 to-burner 2, with proportional drop inipressurc; at the lower side ofy diaphragm 24. The consequentfshiftef ing of the diaphragm serves partially to closeyaltef 19 and thereby reduce the amount of gasy admitted. toi inlet;

22 of mixer-blower 3. 'As a-result,vthe`air. andgasimix@ ture will-be maintained. in theldesiredV proportion for proper combustion at burner 2.. i

Changes in the back pressure within combustion` cham- 1f ber or inner shell 5 due to changes: in the.y duct system;-

etc., to which the heated air and'gases are? delivered: do: not appreciably affect thedelivery,V of mixer-blowenlfl which is a high pressure blower. Buteven a' rather. slight;

change. in the back. pressure willeffect asubstantial change in the volume of the main air ow from main ai;

supply fan 4 which operates at a lower range. A Consequently,` the total volume of heated air and gases discharged yfrom orifice 11 ofcombustionchamber 5 (the sum of the main fan discharge and the burner discharge, which latter is a small proportion of the total) will be substantially affected and since the quantity of'heat is constant, the temperature of such' total discharge will be correspondingly affected. I provide means, however, for automatically compensating for such undesirable effect in the `form of tube 25 leading from combustion chamber S to the upper side of diaphragm 24. The pressure in such tube is, of course, increased by the aforesaid increase in back pressure and the diaphragm is accordingly shifted further to close the gas inlet valve 19. There will accordingly now be a lower proportion of gas in the gasair mixture delivered by the mixer-blower 3 to the burner 2 than was the case before, and this is exactly what is desired since due to the back pressure at the burner the main supply fan 4 is no longer effective to deliver as large a volume of air to the burner as before, such air, of course, being required for complete combustion of the gas in the gas-air mixture delivered to the burner.

Furthermore, due to the reduced quantity of gas now available at the burner, less heat is produced and the same nal temperature of the heated air and gases of combustion deliveredat orice 11 will be maintained despite the reduced volume of air delivered from blower 4. An important object of my invention is thus accomplished, namely that of automatically maintaining a predetermined temperature of the heater discharge despite variations in the back pressure encountered from time to time. Valve 19 and its regulator perform the function of regulating the gas supply in a manner to compensate both for such variations in back pressure at the heater outlet and also for (manual) adjustment of the air inlet shutter 18. It will be understood that such regulator is not per se a part of my invention, being commercially available, but I have employed it in a novel manner. The entire heater may be of quite lightweight construction and readily portable, considerably enhancing its usefulness in the ordinary foundary. It is, moreover, efficient in the production and conservation of heat and is accordingly relatively inexpensive to operate.` Due to its compact arrangement, it is also relatively inexpensive of manufacture.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

I therefore particularly point out and distinctly claim as my invention:

l. In a fuel tired heater having a sheet metal openended shell, a gas tired burner therewithin adapted to heat said shell and to release hot gases therewithin, and a high pressure fan positioned at one end of said shell to drive air past said burner through said shellto an outlet therefrom; an outer housing spaced from and enclosing said shell providing air inlet passages to said fan to admit air thereto from inlets disposed peripherally of such outlet from said shell, whereby cool ambient air will ow to said fan in a direction counter to the ow of air and gases within said shell to cool the latter while preheating such air approaching said fan; a mixer-blower having a said conduit resulting from any reduction in admission of ambient air to said mixer-blower and further to move said valve toward closed position in response to increase in back pressure within said shell tending to reduce air ow therethrough from said fan.

2. A portable fuel tired heater having a base platform, a housing mounted thereon, anl inner sheet metal shell within said housing and spaced therefrom, said shell having an open end projecting from said housing, a fan positionedwithin said housing at the other end of said shell operative to drive'air through said shell and out the open end of the latter, air inlet openings to said housing peripherally of such outlet end of said shell for admission of ambient airto said housing and ow of such air between said shelland housing to said fan in a direction opposite to the flow of air through said shell from said fan, a gas fired burnerl within said shell adapted to heat said shell and to release hot gases therewithin, a constant-speed mixer-blower mounted on said platform having an air inlet thereto and a delivery conduit connected to said burner to deliver a gas-air mixture thereto for combustion, an adjustably louvered air inlet shutter for said air inlet to regulate the admission of ambient air to said mixer-blower, a gas inlet valve adapted to admit gas to said air inlet of said mixer-blower, a regulator operative to adjust said valve in response to pressure differentials, means connecting said regulator to the interior of said shell, further means connecting said regulator to said delivery conduit of said mixer-blower to activate said regulator to adjust said valve to move the latter toward closed position in response to lower pressure in said con duit resulting from reduction in admission of ambient air to said mixer-blower by partial closing of said shutter and further to move said valve toward closed position to reduce admission of gas to said mixer-blower in response to increase in back pressure within said shell tending to reduce air flow through the latter from said fan.

3. The heater of claim 2, wherein said regulator is of the diaphragm type, with said connection to said shell leading to one side of said diaphragm and the connection to said conduit leading to the other side of said conduit.

4. A portable, compact fuel-fired heating apparatus adapted for easy transportation to and from various stations of use, said apparatus including a substantially recdelivery conduit leading to said burner to deliver a gas-l o5 air mixture thereto for combustion, means adapted to regulate admission of ambient air to said blower, a gas inlet valve adapted to admit gas to said blower, a regulator operative to adjust said valve in response to pressure dierentials, means connecting said regulator to the interior of said shell, further means connecting said regulator to said delivery conduit of said blower to establish such pressure differentials at said regulator to activated the latter to adjust said valve to move the same toward closed position in response to lower pressure in tangular platform, a sheet metal shell supported along one side of the platform in the general direction of the greater length of said platform, a gas-tired burner carried within said shell adapted to heat the same and release hot gases therein, a high pressure fan supported on the platform in substantially axial alignment with said shell and adapted to force air into said shell past said burner and out the opposite end of the shell which thereby defines an outlet, an outer housing spaced from and enclosing said shell to provide air inlet passages to said fan and admit air thereto from inlets disposed peripherally of such outlet from said shell, whereby cool ambient air will flow to said fan in a direction counter to the tlow of air and gases within said shell to cool the latter while preheating such air approaching said fan, a mixer-blower carried by said platform laterally of said shell and at a point substantially corresponding to the position of the burner within the shell, a conduit connecting said mixerblower and said burner to transmit a gas-air mixture, means adapted to regulate the admission of ambient air to said mixer-blower, a gas inlet valve adapted to admit gas to said blower, regulating means including a. diaphragm valve to adjust such gas inlet valve, said regulating means being supported laterally of said shell and above the mixer-blower means, means connecting said regulating means to the interior of said shell to move said gas inlet valve toward a closed position in response to back pressure within said shell tending to reduce air iiow therethrough from said fan, and further means connecting said regulating means to said conduit to move said gas inlet valve toward a closed position in response to lower pressure in said conduit resulting from any reduction in admission of ambient air to said mixer-blower.

5. A portable, compact gas-fired heating apparatus adapted to discharge heated gases of substantially constant temperature although of varying volume, said apparatus including a substantially rectangular base platform permitting the entire apparatus to be easily transported to and from various stations of use, a sheet metal shell supported along one side of said base platform in the general direction of the greater length of said platform, a gas-tired burner carried within said shell adapted to heat the same and release hot gases therewithin, a high pressure fan supported on the platform in substantial axial alignment with said shell and adapted to force air into said shell past said burner and out the opposite end of the shell which thereby defines an outlet, an outer housing spaced from and enclosing said shell to provide air inlet passages to said fan and to admit air thereto from inlets disposed peripherally of such outlet from said shell, whereby cool ambient air will flow to said fan in a direction counter to the ow of air and gases Within said shell to cool the latter While preheating such air approaching said fan, a constant-speed mixer-blower carried by said base platform laterally of said shell and at a point substantially corresponding to the position of the burner Within the shell, a delivery conduit connecting said mixerblower and said burner to transmit a gas-air mixture to the latter, said mixer-blower having an air inlet thereto, an adjustably louvered air inlet shutter for said air inlet to regulate the admission of ambient air to said mixerblower, a gas inlet valve adapted to admit gas to said mixer-blower, regulating means including a diaphragm valve to adjust said gas inlet valve, said regulating means being Isupported laterally of said shell and above the mixer-blower', pressure connecting means joining the interior of said shell to one side of the diaphragm of the diaphragm valve to move said gas inlet valve toward a closed position to reduce admission of gas to said mixerblower in response to an increase in back pressure within said shell tending to reduce -air flow through the latter from said fan, and further pressure connecting means joining said delivery conduit to the other side of the diaphragm of said diaphragm Valve to move said gas inlet valve toward a closed position in response to lower pressure in said conduit resulting from reduction in the admission of ambient air to said mixer-blower by partial closing of said shutter, thereby to maintain a predetermined temperature on the discharge of said outlet of the shell release of variations in the volume discharged because of back pressure and the like.

6. The heating apparatus of claim 5 including a motor to drive said fan, a constant-speed motor to drive said mixer-blower, and a safety shut-oi valve supported adiacent and in serial connection With said gas inlet valve.

References Cited in the le of this patent UNITED STATES PATENTS 1,174,003 Gibson Feb. 29, 1916 1,431,633 Clements Oct. 10, 1922 1,943,053 Boisset Ian. 10, 1934 2,015,982 Witzel Oct. 1, 1935 2,756,040 Golden f....-v .t. Iuly 24, 1956 

